TiO2 tailoring the reconstruction of NiMo alloy for stable alkaline water electrolysis

A strong interaction interface is constructed between TiO 2 particles and NiMo nanorods. • NiMo alloy electrodes with and without TiO 2 exhibit different reconstruction processes as both anode and cathode. • TiO 2 tailored NiMo electrodes exhibits excellent activity and stability for over 10,000 h at 500 mA cm −2 in 30% KOH at 80 °C. • The reaction mechanism was systematically studied by in situ Raman spectroscopy and 18 O isotope labeling. The reconstruction process of electrocatalysts plays an important role in the electrocatalytic process, and how to tailor the reconstruction is crucial for the performance and remains greatly challenging. Herein, we demonstrate that TiO 2 can tailor the reconstruction process of NiMo alloy for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) reactions. NiMoO 4 microrods arrays adsorbed with titanium butoxide on its surface are converted into TiO 2 modified NiMo alloy under high-temperature reduction. NiMo alloy electrodes with and without TiO 2 exhibit different reconstruction processes as both anode and cathode under simulated industrial conditions (30% KOH, 80 °C). With TiO 2 , the cathode and anode are reconstructed into ultrafine Ni(OH) 2 nanosheets coated on NiMo alloy and ultrafine NiOOH nanosheets, respectively. Without TiO 2 , NiMo alloy electrodes are reconstructed into large-sized Ni(OH) 2 or NiOOH nanosheets on the cathode or anode. The TiO 2 tailored NiMo electrodes exhibit low overpotentials of 29 mV for HER and 213 mV for OER at a current density of 10 mA cm −2 in 1 M KOH at 25 °C. Moreover, an electrolytic cell assembled by them as both cathode and anode electrodes can maintain 1.8  V at a current density 500 mA cm −2 with stable running for over 10,000 h in 30% KOH at 80 °C. Mechanism studies indicate that TiO 3 2− ions intercalate into the interlayer of Ni(OH) 2 , inhibiting the dissolution of Mo and controlling the size of Ni(OH) 2 , and the bond lengths of Ni O and Ni Mo bonds are shortened, which effectively enhance catalytic activity and stability. Download: Download high-res image (60KB) Download: Download full-size image